Formation of casein-based triglyceride amorphous solid dispersions

Amorphous solid dispersions (ASDs) occur when hydrophobic compounds prone to crystallizing are stabilized in a non-crystalline state by a solid polymer matrix. Little is known about their formation in food systems. Palm kernel stearin (PKS) and tristearin (SSS) were used as model hydrophobic compounds to form casein-based ASDs. PKS and SSS were dispersed in ethanol/water solutions (0–100 % v/v) at 22 and 60 °C to determine short (30 min) and long-term (15 h) turbidity and emulsion breakdown. Then, PKS or SSS together with micellar casein were suspended in ethanol/water (0–60% v/v; 22 and 60 °C), followed by solvent removal with two-steps (centrifugal vacuum concentration and freeze drying) or one-step (freeze drying) to create ASDs. The crystallization/melting behaviors observed by differential scanning calorimetry (DSC) and signals obtained by X-ray diffraction (XRD) were consistent with the formation of ASDs for PKS-casein powders initially formed by dispersing PKS and casein in 40–60% v/v ethanol water at 60°C with single-step drying. SSS-casein powders showed DSC thermograms consistent with the formation of ASDs but contradicted XRD which indicated the presence of crystallinity in all powders. The present study demonstrated casein-based ASDs can be successfully formed in a model system, but further research is required to understand their functionality in food systems.